Spring fastener with highly improved lever/angle pulling force

[0001] This application claims priority of provisional patent application 60/520/807, filed Nov. 17, 2003, which is incorporated herein by reference in its entirety.

[0002] This invention relates to spring fasteners characterized by a structure having a cavity in which an extension or rib of a first part, such as a plastic panel for example, may be engaged, and they are also suitable to be engaged reversibly in a slot of second part, such as a metal sheet or the frame of a car for example. The invention also pertains an assembly of the first and the second part as connected to each other through the fastener, as well as vehicles comprising such assemblies.

[0003] A number of fasteners have been used in the past for securing one object on another object, as for example, securing an article such as for example a plastic sheet on a metal or other rigid plastic sheet. However, the fasteners of the type, which are improved by the advances of the present invention, and being used presently, have a rather low ratio of insertion force to removal force. In other words, they require considerable force to be inserted into a slot in order to provide adequate removal resistance in order to be removed from the slot. This is ergonomically inferior performance, and the operators may suffer miscellaneous ailments, while productivity is also considerably undermined. In addition the fasteners of the present state in the art suffer from rather inferior Lever/Angle Pulling force.

[0004] Lever/Angle pulling force is defined as the force required to separate one part from another part connected with a fastener by pulling said parts apart, not straight away form each other, but sideways from each other, as will be described in more detail hereinbelow.

[0005] One of the major objectives of the present invention is to provide fasteners of considerably higher Lever/Angle pulling force than the fasteners of the present state in the art.

[0006] Recently, a fastener has been disclosed in U.S. Pat. No. 6,718,599 B2, which is incorporated herein by reference, characterized by ergonomically balanced removal to insertion force ratio. However, even in this case, the Lever/Angle pulling force is relatively low.

[0007] Examples of other state in the art fasteners are disclosed in U.S. Pat. No. 6,381,811 (Smith et al.), U.S. Pat. No. 6,353,981, U.S. Pat. No. 6,074,150 (Shinozaki et al.), U.S. Pat. No. 5,987,714 (Smith); U.S. Pat. No. 5,887,319 (Smith); U.S. Pat. No. 5,542,158 (Gronau et al.); U.S. Pat. No. 5,422,789 (Fisher et al.), U.S. Pat. No. 5,373,611 (Murata); U.S. Pat. No. 5,314,280 (Gagliardi); U.S. Pat. No. 5,095,592 (Doerfling); U.S. Pat. No. 4,701,984 (Wyckoff), U.S. Pat. No. 4,792,475 (Bien); U.S. Pat. No. 4,683,622 (Ohelke); U.S. Pat. No. 4,609,170 (Schnabl); U.S. Pat. No. 4,245,652 (Kelly et al.); U.S. Pat. No. 3,864,789 (Leitner); U.S. Pat. No. 3,673,643 (Kindell); U.S. Pat. No. 3,525,129 (Holton); U.S. Pat. No. 2,825,948 (Parkin); U.S. Pat. No. 2,607,971 (Bedford, Jr.); U.S. Pat. No. 2,542,883 (Tinnerman); U.S. Pat. No. 2,329,688 (Bedford, Jr.); U.S. Pat. No. 2,322,656 (Murphy), among others.

[0008] U.S. Pat. No. 5,919,019 (Fisher) provides fasteners which can only be permanently installed into a slot; they can only be inserted but not extracted without damage to parts of the fastener. The major engagement is performed by spring strips, while frictional portions of the fastener pass through the slot with at most slight compression, and immediately after the insertion of the fastener they are located in slightly spaced or barely contacting relation with the edges of the slot. They are only activated for engagement after the insertion of a bolt into a hole at the base plate. Thus, the profound effect of the increased removal to insertion ratio (explained in detail hereinbelow) is not recognized, mentioned, or implied. Thus, the intentionally provided distance of the frictional portions away from the edges of the slot by Fisher, during insertion and before use of the bolt, teaches actually away from the instant invention, which recognizes and takes full advantage of the increased removal to insertion ratio by an engagement region having a hindrance portion. As a matter of fact, if the engagement surfaces of the instant invention were located in slightly spaced or barely contacting relation with the edges of the slot, no engagement at all would take place upon insertion of the fastener of this invention into the slot.

[0009] U.S. Pat. No. 6,141,837 (Wisniewski) describes a spring fastener comprising bulbous and outwardly projecting portions, which assist in preventing withdrawal of the clip and associated molding from an aperture of a vehicle frame. However, “bulbous projections” are necessarily voluminous, take most of the space between the “reverse bents”, and unless they are manufactured within tight tolerances with regard to the thickness of the frame, the “base plates” do not sit on the frame (see also the Figures), rendering the structure unstable.

[0010] U.S. Pat. No. 6,203,240 B1 (Hironaka et al.), U.S. Pat. No. 5,129,768 (Hoyle et al.), U.S. Pat. No. 5,092,550 (Bettini), U.S. Pat. No. 4,981,310 (Belissaire), U.S. Pat. No. 4,712,341 (Harris, Jr. et al.), U.S. Pat No. 4,595,325 (Moran et al.), U.S. Pat. No. 4,431,355 (Junemann), U.S. Pat. No. 4,133,246 (Small), and U. S. Pat. No. 2,424,757 (F. Klump, Jr.) are directed to plastic or metal fasteners which are designed to be just inserted into the slot of a panel, but not extracted without damage to the fastener (if such extraction would be attempted from the front side; the side from which the fastener is inserted into the panel, since the back part of the panel is not reachable in the cases, wherein such types of fasteners are used).

[0011] None of the above disclosures of the present state in the art provide satisfactory Lever/Angle pulling force.

[0012] As aforementioned, this invention relates to spring fasteners characterized by a structure having a cavity in which the rib of a first part, such as a plastic panel for example, may be engaged, and they are also suitable to be engaged reversibly in a slot of second part, such as a metal sheet or the frame of a car for example. The invention also pertains an assembly of the first and the second part as connected to each other through the fastener, as well as vehicles comprising such assemblies. The spring fasteners of the present invention are characterized by a Lever/Angle pulling force, which is considerably higher than that characterizing spring fasteners of the present state in the art.

[0013] A very unexpected increase in Lever/Angle pulling force is attained by forming a side-cut section, especially at least partially bent outwardly, disposed in critical positions of the spring fastener, as will described in more detail hereinbelow.

[0014] Outwardly means away from the fastener.

[0015] More particularly, this invention pertains a spring fastener comprising a first side and a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side, a bottom portion wherein the first side and the second side are connected, and a top portion, the first side comprising a first spring, the first spring connected to the first side in the vicinity of the bottom portion, the second side comprising a second spring, the second spring connected to the second side in the vicinity of the bottom portion, each of the first and second engagement springs comprising a peak, a free end in the vicinity of the top portion, and an engagement region between the peak and the front end, at least one spring further having a side-cut section or notch, preferably in the vicinity the respective peak, the side-cut section or notch oriented substantially parallel to the peak. It is preferable, however, that each spring has two side-cut sections, one opposite to the other.

[0016] The side-cut sections or notches have an upper edge and a lower edge. It is highly preferable that at least one of the lower edges, and even more preferable that all lower edges are at least partially bent outwardly.

[0017] This invention further pertains an assembly comprising:

[0018] a spring fastener comprising a first side and a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side, a bottom portion wherein the first side and the second side are connected, and a top portion, the first side comprising a first spring, the first spring connected to the first side in the vicinity of the bottom portion, the second side comprising a second spring, the second spring connected to the second side in the vicinity of the bottom portion, each of the first and second engagement springs comprising a peak, a free end in the vicinity of the top portion, and an engagement region between the peak and the front end, at least one spring further having a side-cut section, preferably in the vicinity the respective peak, the side cut section oriented substantially parallel to the peak, and having an upper edge and a lower edge;

[0019] a first part comprising a rib inserted into the cavity of the spring fastener and engaged to the first and second barbs; and/or

[0020] a second part comprising a slot, the slot having a width and edges, the fastener being disposed in the slot in a manner that the edges of said slot are engaged to the engagement regions of the spring fastener.

[0021] In addition, this invention is related to a vehicle which comprises an assembly, the assembly comprising vehicle comprising an assembly, the assembly comprising:

[0022] a spring fastener comprising a first side and a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side, a bottom portion wherein the first side and the second side are connected, and a top portion, the first side comprising a first spring, the first spring connected to the first side in the vicinity of the bottom portion, the second side comprising a second spring, the second spring connected to the second side in the vicinity of the bottom portion, each of the first and second engagement springs comprising a peak, a free end in the vicinity of the top portion, and an engagement region between the peak and the front end, at least one spring further having a side-cut section, preferably in the vicinity the respective peak, the side cut section oriented substantially parallel to the peak, and having an upper edge and a lower edge;

[0023] a first part comprising a rib inserted into the cavity of the spring fastener and engaged to the first and second barbs; and

[0024] a second part comprising a slot, the slot having a width and edges, the fastener being disposed in the slot in a manner that the edges of said slot are engaged to the engagement regions of the spring fastener.

[0025] It is preferable that the fastener comprises hindrance portion within the engagement region, and more preferable that the side-cut section is disposed within the engagement region. It is further highly preferable that the side-cut section has a triangular shape.

[0026] The spring fastener of the present invention may further comprise a recess within the engagement region, in the vicinity of the top end.

[0027] The hindrance portion may have any suitable structure, which hinders to a desired degree the removal of the spring fastener from the slot described above. It is preferable, however, that said hindrance portion comprises one structure selected from ripple, side rib, upward solid bent extension parallel to the peak and the optional recess, knurled region, bent teeth, each having a depth, a bump or bulbous formation, and a combination thereof.

[0028] The presence of a single ripple in the vicinity of the peak is more preferable according to this invention, and it is even more preferable that the ripple has a back side with a curvature of a gradually decreasing slope. Preferably, the gradually decreasing slope has the shape of an arc in the range of 50–70 degrees with a radius in the range of 0.03–0.05 mm.

[0029] More details regarding preferred configurations of engagement regions are described in Non-provisional patent application Ser. No. 10/164,963, filed Jun. 7, 2002, and its respective Patent Application Publication US 2002/0194710 A1, Pub. Date Dec. 26, 2002, both of which are incorporated herein by reference.

[0030] It is further preferable that the spring fastener of this invention further comprises first barbs and second barbs being cut portions of the respective first and second side of the spring fastener, originating from the vicinity of the top portion of said spring fastener and directed toward the bottom portion the spring fastener, the first barbs and the second barbs comprising respective first back sections and first front sections, the first sections being bent portions of the first back sections, and second back sections and second front sections, the second front sections being bent portions of the second back sections.

[0031] The barbs are preferably selected from a group consisting essentially of:

• • [0032] first barbs being outer barbs and second barbs being inner barbs;
  • [0033] first barbs being outside outer barbs and second barbs being inside outer barbs; and
  • [0034] first barbs being inner barbs and second barbs being inner barbs.

[0035] It is preferable that the barbs which are cut from their respective side, are flexible, and bent in the vicinity of their respective front end as described for example in U.S. Pat. No. 6,279,207 B1, which is incorporated herein by reference, and more particularly in FIG. 1A of said patent, with an angle of bent in the range of 5–25 degrees.

[0036] The barbs are considered to be flexible if they do not cause the width W3 (FIG. 1B) to increase more than 30%, preferably 20%, and more preferably 10%, when the rib 46 is inserted into the cavity 19 of the fastener 10 (FIG. 4A), and provided that the first object 46 is adequately hard to hinder the barbs 36 from substantially digging into it.

[0037] Regarding the outside outer barbs, it is preferable that their front points are at a distance from the second side smaller than the thickness of the material from which the spring fastener was made. This is to avoid interconnection of the fasteners, when said fasteners are stored in bulk.

[0038] The barbs may have variable width along their length, or they may have substantially the same width along their length. Further, the front points of the barbs may be toothed.

[0039] More details regarding our preferred bent barbs are also described in U.S. Pat. Nos. 6,279,207 B1 and 6,691,380 B2, both of which are incorporated herein by reference.

[0040] The spring fastener of the instant invention may further comprise a molded elastic body at least under the top portion of said spring fastener for sealing purposes. Such arrangements are disclosed in U.S. Pat. No. 6,353,981 B1, which is incorporated herein by reference. Other sealing arrangements are also included in the instant invention, as described for example in U.S. Pat. No. 6,527,471 B2, which is also incorporated herein by reference.

[0041] In another embodiment, the spring fastener of the instant invention may further comprise:

[0042] an elastic body comprised of at least a gasket, the gasket extending away from the cavity in the vicinity of the top portion of the fastener and enclosing at least partially the cavity; and

[0043] a casing surrounding at least partially the spring fastener under the top portion, except at least the engagement section of each engagement spring, the casing also at least partially surrounding the cavity and such portion of the elastic body which at least partially encloses the cavity;

[0044] wherein the casing has lower ultimate elongation, higher Shore hardness, and higher shear strength than the elastic body. Thus, preferably the casing is substantially non-elastic.

[0045] Such arrangements are disclosed in U.S. Pat. Nos. 6,381,811 B2, 6,497,011 B2, 6,527,471 B2, and 6,648,547 B2, all of which is incorporated herein by reference.

[0046] According to the present invention, any embodiments of fasteners described above and their equivalents may be used in any assembly in which the first part and/or the second part are connected with the fastener, as well as in any vehicle comprising such an assembly or such a fastener or its equivalents.

[0073] As aforementioned, this invention relates to spring fasteners characterized by a structure having a cavity in which the rib of a first part, such as a plastic panel for example, like a pillar for example, may be engaged, and they are also suitable to be engaged reversibly in a slot of second part, such as a metal sheet for example, like the frame of a car for example. The invention also pertains an assembly of the first part connected to the fastener, the first and the second part connected to each other through the fastener, as well as vehicles comprising such assemblies.

[0074] More particularly, as better shown in FIGS. 1, 1A and 1B, the invention pertains a spring fastener 10 comprising a first side 12 and a second side 14 opposite the first side 12. The first side 12 is connected to the second side 14 forming a U-shaped structure which has a cavity 19 between the first side 12 and the second side 14. The fastener 10 also has a bottom portion 16, wherein the first side 12 and the second side 14 are connected. It further has a top portion 18a and 18b (collectively 18).

[0075] In all cases, numerals referring to the first side 12 contain the letter “a”, while numerals referring the second side 14 contain the letter “b”. The same numerals without the letters “a” or “b”, refer collectively to the respective elements of both sides.

[0076] The first side 12 comprises a first engagement spring 20a, which is connected to the first side 12 in the vicinity of the bottom portion 16.

[0077] The second side 14 comprises a second engagement spring 20b, which is connected to the second side 14, also in the vicinity of the bottom portion.

[0078] Each of the first and second engagement springs 20a and 20b may preferably, but not necessarily, have a first and second recess, 24a and 24b, respectively, as shown in FIGS. 1A and 1B, and a first and second free end, 22a and 22b, respectively, in the vicinity of the top portion 18 (18a and 18b, respectively). Each spring also comprises a first and a second peak, 26a and 26b, respectively, and a first and second engagement region, 28a and 28b, respectively.

[0079] Preferably, within the engagement region, and more preferably in the vicinity of the peaks 26, there are side-cut sections 8a and 8b on the spring sides consisting of side-cuts 8a and 8b (collectively 8), respectively, preferably of triangular shape, which render the lever/angle pulling force considerably higher than it would have been in their absence. Each one of the side-cuts or notches 8 has an upper edge 7 (7a and 7b), and a lower edge 9 (9a and 9b). It is highly preferable that the lower edges 9 (9a and 9b) are at least partially bent outwardly, as better illustrated in FIG. 1C. It is evident that the invention includes the case that only one side-cut section may be present.

[0080] As aforementioned, lever/angle pulling force is defined as the force required to separate one part from another part connected with a fastener by pulling said parts apart, not straight away form each other, but sideways from each other.

[0081] It is highly preferable also, that the engagement regions 28, further comprise a first and second hindrance portion, 29a and 29b, respectively, between the bents 26 and the front ends 22.

[0082] The hindrance portions provide increased removal force, when the fastener 10 is pulled by a rib or extension 46 (FIG. 4B) of a first part 44 (FIG. 4) engaged to the first and second barbs, 36a and 36b, respectively, after the fastener 10 has been inserted into a slot 50 of a second part 48 (FIG. 4), the slot 50 having a slot width W2 (FIGS. 4 and 4C) and edges 51 (FIG. 4C) on which edges the engagement regions 28a and 28b are engaged. The removal force is measured by pulling rib 46 of the first part 44 straight away from the second part 48 in the vicinity of point F1.

[0083] The increased removal force is due to the hindrance portions 29a and 29b (FIG. 4C), which in this particular case comprise single ripples with only back sides 34, as it will be explained at a later point in more detail. According to this invention, the engagement portions 28a and 28b and the hindrance regions 29a and 29b are required to be such that the fastener 10 can be extracted from the slot 50 when pulled by the rib 46 without damage to said fastener 10, and with a higher force than a force required in the absence of the hindrance portions 29a and 29b.

[0084] The lever/angle pulling force is measured by pulling the first part 44 apart from the second part 48, not straight away, but sideways from each other, that is for example by pulling the first part 44 from a point F2 away from the rib 46, such as the edge 45 for example of the first part 44, such as an automotive pillar for example.

[0085] In different applications, the exact position of point F2 may be different, as well as the required increase in lever/angle force by the use of the side-cut sections.

[0086] The first side 12 also comprises first barbs 36a, which in the case shown in FIGS. 1A and 1B are outer barbs, since they are disposed in an outer portion of the first side 12. The barbs 36a have first front ends 38a. In the particular cases of FIGS. 1A and 1B, the first barbs 36a are bent inwardly in the vicinity of the front ends 38a, according to a highly preferred embodiment of the instant invention.

[0087] The second side 14 comprises second barbs 36b, which in the case of FIGS. 1A and 1B are inner barbs, since they are disposed in an inner portion of the second side 14. The second barbs have second front ends 38b. In this particular case of FIGS. 1A and 1B the second barbs 36b are also bent inwardly in the vicinity of the front ends 38b, according to a highly preferred embodiment of the instant invention.

[0088] In the case of FIG. 1, the barbs 36a and 36b are straight.

[0089] This invention further pertains an assembly 11, as better shown in FIG. 4B, comprising a spring fastener as described above or in the embodiments and their equivalents presented hereinbelow, and a first part 44 (FIG. 4) comprising a rib 46 (FIG. 4A) inserted into the cavity 19 of the spring fastener 10 and engaged to the first and second barbs 36a and 36b.

[0090] Further, this invention further pertains an assembly 1, as better shown in FIG. 4B, comprising a spring fastener as described above or in the embodiments presented hereinbelow; a first part 44 (FIG. 4) comprising a rib 46 (FIG. 4A) inserted into the cavity 19 of the spring fastener 10 and engaged to the first and second barbs 36a and 36b; and a second part 48 (FIGS. 4 and 4B) comprising a slot 50, which slot 50 has a width W2 and edges 51 (FIG. 4C), so that the edges 51 of said slot are engaged to the engagement regions 28a and 28b of the spring fastener 10. In this case also, the requirement exists that by pulling the rib 46, the fastener 10 is extracted from the slot 50 without damage to the fastener 10, and with a higher force than a force required in the absence of the hindrance portions 29a and 29b.

[0091] In addition, this invention is related to a vehicle which comprises an assembly 11, as described above.

[0092] In operation of the above embodiments, the spring fastener 10 of the present invention is intended to connect a first part, such as a panel 44 for example, which panel may have a rib 46, with a second part, such as a frame 48 of a car for example, having a slot 50, as illustrated in FIG. 4.

[0093] The rib 46 of the panel 44 is preferably first inserted into the cavity 19 of the fastener 10 (see FIG. 4A), where, it is secured by barbs 36a and 36b. Then, the fastener 10, which has been secured on the extension 46 of the panel 44, is inserted into the slot 50 of the frame 48, as better shown in FIG. 4B. However the sequence inserting the fastener may be the opposite.

[0094] In this manner, the first part, exemplified by panel 44, has been connected on the second part, exemplified by frame 48, through the fastener 10 of the instant invention.

[0095] In most practical applications, the length Le (see FIG. 4A) of the engagement regions 28 is not higher than 2–4 mm, while the thickness T_f of the frame 48 (see FIG. 4B) may vary in most occasions in the range of 0.5 to 2 mm. This fact makes it rather difficult to form large hindrance portions. Thus, The “bulbous projections” suggested by U.S. Pat. No. 6,141,837 (Wisniewski) are necessarily too bulky and voluminous, take most of the space between the “reverse bents” (engagement regions between the peak and the recess in the case of the instant invention), and unless they are manufactured within tight tolerances with regard to the thickness of the frame (which in practice may vary considerably), the “base plates” (top portions in the case of the present invention) do not sit on the frame (see also Wisniewski's Figures), rendering the structure considerably unstable.

[0096] According to this invention, and particularly for ergonomic purposes combined with practical aspects, it is highly preferable that the force to insert the rib of the first part into the cavity of the spring fastener should be less than 40 lbs, preferably less than 15 lbs, and even more preferably less that 10 lbs; the force to insert the spring fastener into the slot should be less that 30 lbs, preferably less than 15 lbs, and even more preferably less than 10 lbs; and the force to extract the spring fastener from the slot should be in the range of 30–100 lbs, and preferably in the range of 50–70 lbs.

[0097] It was unexpectedly found by the inventors that in order to achieve the above results, the hindrance portions should comprise rather minute elements, and not the huge structural components disclosed in the art. Such huge structural components render respective fasteners to be irreversibly inserted into slots. Any attempt to extract these fasteners from the side of the panel that they were inserted would result in destruction of the fasteners.

[0098] According to this invention, the hindrance portions 29a and 29b may comprise minute elements, such as ripples, upward solid bent extensions parallel to the peaks and the recesses, knurled regions, bent teeth, each having a depth, the depth of which does not exceed preferably 0.2 mm, and more preferably 0.1 mm. Any person of ordinary skill in the art would not expect that elements having such minute depths would have such great impact in force balances as the aforementioned ones.

[0099] The depth for any element is substantially defined in the same manner as defined at a later point for the ripples.

[0100] Although this invention includes any structure which satisfies the claims, such as for example upward solid bent extensions parallel to the peaks and the recesses, knurled regions, bent teeth, as described in at least one of the provisional patent application 60/301,364, filed Jun. 25, 2001, 60/327,814, filed Oct. 9, 2001, and 60/353,515, filed Feb. 1, 2002, U.S. Pat. No. 6,718,599 B2, and U.S. Pat. No. 6,745,440 B2, all of which are incorporated herein by reference, and as long as their depth does not exceed 0.2 mm, the most preferable configuration is one that comprises at most three ripples having a preferable depth not exceeding 0.2 mm, and more preferably not exceeding 0.1 mm. It is more preferable that the hindrance portion comprises not more than two ripples, and even more preferable one ripple. Structures with one to three two-sided ripples 30 are shown in FIGS. 3B to 3D, respectively.

[0101] FIG. 2 illustrates a spring fastener 10 according to this invention, wherein the hindrance portion 29 comprises one two-sided ripple 30 and bent barbs 36.

[0102] The most efficient and effective case, however, according to this invention, is the use of only one single-sided ripple 30, as shown for example in FIGS. 1A and 3A.

[0103] The operation of these embodiments is substantially the same as the operation of the previous embodiments.

[0104] It is preferable that each ripple 30 is in the form of a depression, as better shown in FIG. 5. The depression has a deepest part Z, a front side 32, a back side 34, and a width W1. The hindrance portion 29 has a surface E, and the depth D of each ripple 30 is defined as the distance between the surface E of the hindrance portion 29 and the deepest part Z of the respective ripple 30.

[0105] For better performance, the ripple width is larger than the depth of the ripple, and preferably the ripple width is at least twice the size of the depth of the ripple. The ripple width is preferably in the range of 0.1 to 0.5 mm and the ripple depth is in the range of 0.01 to 0.1 mm, as aforementioned.

[0106] In a preferred embodiment, the back side 34 of the ripple 30 is substantially linear and has a slope S in the range of 15 to 30 degrees with regard to the general plane of the surface E of the hindrance portion 29, and it is also preferable that the front side 32 has a higher slope than the back side. The slope of the front side is measured in the same manner as the slope of the back side. Thus, if the front side 32 is substantially perpendicular to the surface E, the slope is substantially 0 degrees, while if the front side 32 is substantially parallel to the plane of surface E and the continuation of the deepest part Z, it is substantially 90 degrees.

[0107] It is, however, highly preferable that the back side 34 has the form of a curvature with a gradually decreasing slope. For example, the gradually decreasing slope of back side 34 may have the shape of an arc corresponding to an angle A1, preferably in the range of 50–70 degrees, with a radius R, preferably in the range of 0.03–0.05 mm., as better shown in FIG. 5A.

[0108] This configuration is of extreme importance in most occasions, because during vibrations, the edges 51 of the slot 50 (FIG. 4C) slide smoothly on the engagement regions 28 as well as the hindrance portions 29 during operation, and when they reach the back sides 34 of the single-sided ripples 30 (FIG. 5A), they continue sliding smoothly finding increasingly higher resistance in a continuous manner, which eliminates any rattling noises. Such rattling noises would be present in a case that the edges 51 would hit abrupt obstacles or would suddenly jump down, even without hitting such obstacles.

[0109] The barbs are preferably selected from a group consisting essentially of:

• • [0110] first barbs 36a being outer barbs, and second barbs 36b being inner barbs, as better shown in FIG. 6 (blank before forming) and 6A (side view);
  • [0111] first barbs 36a being outside outer barbs, and second barbs 36b being inside outer barbs, as better shown in FIG. 7 (blank before forming); and
  • [0112] first barbs 36a being inner barbs, and second barbs 36b being inner barbs, as better shown in FIG. 8 (blank before forming).

[0113] In operation, the barbs engage on the rib 46 of the first part 44, and when an adequate pulling force is applied on the firs part 44, the fastener remains on said first part 44, but is extracted from the slot 50.

[0114] The spring fastener 10 may also comprise relief openings 42a and 42b in the vicinity of the bottom 16 of the spring fastener 10, as better shown in FIG. 6 (blank before forming). These relief openings facilitate the insertion of the fastener into the slot 50.

[0115] The spring fastener 10 may further comprise additional lower barbs 40a and 40b pointing inwardly and originating form the vicinity of the bottom portion 16 of the first side and the second side, respectively, of the fastener 10, as better shown in FIG. 9 (blank before forming).

[0116] In another embodiment, better illustrated in FIG. 10 (blank before forming), the first side of the spring fastener 10 has only one upper barb 36a and one lower barb 40a, while the second side also has also only one upper barb 36b and only one lower barb 40b, in a manner that the upper barb of one side faces the lower barb of the other side and vice versa.

[0117] The barbs 36 may have variable width along their length, as illustrated in for example in FIGS. 6–10, or they may have substantially the same width along their length as better shown in FIG. 11. Further, the front points of the barbs 36 may be toothed, as illustrated in FIG. 12.

[0118] Regarding outside outer barbs 36, it is preferable that their front points 38 are at a distance C from the second side 14 smaller than the thickness T of the material from which the spring fastener 10 is made, as better shown in FIG. 1B. This is to avoid interconnection of the fasteners, when said fasteners are stored in bulk.

[0119] It is preferable that the barbs are cut from their respective side, are flexible, and bent in the vicinity of their respective front end as described for example in U.S. Pat. No. 6,279,207 B1, which is incorporated herein by reference, and more particularly in FIG. 1A of said patent, with an angle of bent in the range of 5–25 degrees.

[0120] It is also preferable that the fastener 10 has a width W3 (FIG. 1B) in the vicinity of the top portion 18 of the fastener 10, which is at least 60%, and more preferably at least 70%, as wide as the slot width W2 (FIG. 4C). Thus, it is preferable that the whole fastener complies with this requirement, or at least a portion in the vicinity of the top. This is to avoid reversal of the direction and failure of the barbs 36, when and if the rib 46 is forcefully pulled away from the second part 48 (FIG. 4B).

[0121] With respect to the engagement regions 28, it is preferable that these regions are at least partially wider than the rest of the respective engagement springs 20 (see for example FIG. 6).

[0122] The more barbs are present, or the more bent their front points are, the stronger the engagement of the rib 46 in the cavity 19. However, in many occasions it is desirable that this engagement is not so strong so as to destroy the integrity of the fastener or the rib, when an adequate force is applied to separate the fastener 10 from the rib 46.

[0123] The spring fasteners 10 of the instant invention may have two engagement springs 20 at the edges of each side instead of one engagement spring 20 in substantially the middle portion of each side (see for Example FIG. 10).

[0124] The spring fastener 10 of the instant invention may further comprise a molded elastic body 54 at least under the top portion 18 of said spring fastener 10, as better shown in FIG. 13. Such arrangements are disclosed in U.S. Pat. No. 6,353,981 B1, which is incorporated herein by reference.

[0125] The operation of this embodiment is similar to the operation of the previously described embodiments with the difference that the elastic body provides moderate sealing properties to the fastener when the fastener is inserted into the slot.

[0126] In another embodiment, the spring fastener of the instant invention may further comprise:

[0127] an elastic body 54 comprised of at least a gasket 56, the gasket 56 extending away from the closed cavity 19 in the vicinity of the top portion 18 of the fastener 10 and enclosing at least partially the cavity 19; and

[0128] a casing 58 surrounding at least partially the spring fastener under the top portion 18, except at least the engagement region 28 of each engagement spring 20, the casing 58 also at least partially surrounding the cavity 19 and such portion of the elastic body 54 which at least partially encloses the cavity;

[0129] wherein the casing 58 has lower ultimate elongation, higher Shore hardness, and higher shear strength than the elastic body 54;

[0130] as better shown in FIG. 14.

[0131] The presence of lips 60 improves considerably the sealing properties of the elastic body.

[0132] Such arrangements are also disclosed in U.S. Pat. No. 6,381,811 B2, which is incorporated herein by reference.

[0133] The operation of this embodiment is similar to the operation of the previously described embodiments with the difference that the combination of the elastic body 54 with the casing 58 provide outstanding sealing properties to the fastener 10 when the fastener 10 is inserted into the slot 50, and the casing itself facilitates the insertion of the fastener 10 into the slot 50.

[0134] According to the present invention, any embodiments of fasteners described above and their equivalents may be used in any assembly in which the first part and the second part are connected with the fastener, as well as in any vehicle comprising such an assembly or such a fastener or its equivalents.